I haven't been able to play as much as I have wanted to lately, but the Chandelure advice definitely seems like it would work well. I went back and looked at my own gameplay and I noticed I do 6X a lot more than I should, where I could double-team dodge overheat and the like if I used 5Y.
Against Darkrai, looks like you have to CADC through his zoning. Then you can get in through Spark, QA, or CA, depending on the situation. Looks like you play it a lot like you suggested against Chandelure. Far enough away he can't hard engage, but close enough he can't hard zone and you can punish misinputs. fY and homing attack don't do well (and tbh QA gets beaten against a lot of his moves it seems).
Thanks for the link to the vids! Spy is awesome